Institute for Energy Efficient Buildings and Indoor Climate

Christian Vering

2

The Institute

■ Founded 2007

■ Interdisciplinary group with more than 100

employees

≡ 2 Professors

≡ 7 Team leaders

≡ About 50 Research associates

≡ Staff

■ More than 1200 m² lab space

≡ Labs

≡ Two experimental facilities

■ Funding

≡ National public funding: BMWi, BMBF

≡ International public funding: EU

≡ Industrial projects

Industrial partners

3

Research Areas

HVAC Systems

Building Energy Systems

Building Automation

Urban Energy Systems

Holistic Building Design &

Management

User behavior and

comfort

En

erg

yE

ffic

ien

tB

uild

ing

s

an

dIn

do

or

Clim

ate

ICT in Distributed Energy

Systems

Au

tom

atio

n o

fC

om

ple

x

Po

we

r S

yste

ms

Arc

hite

cts

an

d C

ivil

En

gin

ee

rin

g:

Hu

ma

n in

Bu

ildin

gs

Low GWP Investigations in Aachen

5

Heat supply in buildings

Coefficient of Performance

𝐶𝑂𝑃 =ሶ𝑄H,K

𝑃el,V~

ΔℎV

(Π Τ(𝑅 𝑀) − 1)

Seasonal COP

𝑆𝐶𝑂𝑃 =Σ ሶ𝑄H,iΣ𝑃el,j

ሶ𝑄U

𝑃el,V 𝑃el,Hydr

Σ ሶ𝑄H,𝑖ሶ𝑄H,K

ሶ𝑄H,Z

𝑃el,Z

Optimization necessary

𝑃el,Eis

System control

𝑃el,Luft

6

Refrigerant vs. system performance

Seasonal COP

𝑆𝐶𝑂𝑃 =Σ ሶ𝑄H,iΣ𝑃el,j

Σ ሶ𝑄H,𝑖

■ Refrigerant Choice

Direct emissions

Operational costs

■ Electricity for operation

Indirect emissions

Operational costs

Indirect emissions

Investments

Economic and ecologic assessment of saving potentials due to

alternative refrigerants

Coefficient of Performance

𝐶𝑂𝑃 =ሶ𝑄H,K

𝑃el,V~

ΔℎV

(Π Τ(𝑅 𝑀) − 1)

Darstellung in Anlehnung an: A. Giebelhaus et al., „Design and control of adsorption chiller systems based on dynamic optimisation“, Heat Powered Cycle Conference 2018.

7

Impact of design and operation

Economic and ecologic saving potential assessment

System component design

ሶ𝑄H,K, 𝑉PS

Operational costs decrease

Investments increase

Optimal structure design

minimizes costs

Operation

Optimal process operation

minimizes costs

ሶ𝑚

Operational costs increase

Investments decrease

8

Simultaneous consideration of design and operation

System structure and process design for heat pump

systems with refrigerant

Optimal process operation

minimizes costs

Optimal structure design

minimizes costs

Nonlinear interactions of both

Simultaneous method necessary Dimensioning = Design + Operation

Large Scale ProjectsUrban Energy Lab 4.0

Human

Centred

Environments

Advanced

Façade

Systems

Natural

refrigerant

Lab

Local Grid

Control

10

Natural Refrigerant Lab (OP EFRE Funding)Hardware-in-the-Loop Test Facility

11

HiL setup

Coupler Simulation

Hardware

Action

Reaction

12

HiL setup

Simulation

Heat pumpDHW

BS

Heat pump system

Climatechamber

Hydraulic test bench

𝑇amb, 𝜑

𝑇fl/reሶ𝑉Δ𝑝

Data exchange

13

Heat Pump Modelling

14

Object orientated architectural approach (BauSIM 18/ECOS 18/MC19/GL2020)

■ Goal modularity: Variable number of interconnecting components

■ Goal scalability: Easily adaptable component sizes

Application layer

Interconnection layer

Component layer

AccuracySimulation Speed

Trade-off

15

Component based modelingRefrigerant (IBPSA Project 1/ GL2020)

Fluid model development

■ R134a

■ R32

■ R407C

■ R410A

■ R290

■ R744

■ Open Source Development:

https://github.com/ibpsa/modeli

ca-ibpsa/pull/1180

Refrigerant

Compressor

Condenser

Expansion valve

Evaporator

System modeling

Control bus

16

Fluid model development

■ Helmholtz-Equation of State

≡ 𝛼 𝜏, 𝛿 =𝑓 𝑇,𝜌

𝑅𝑇= 𝛼ig(𝜏, 𝛿)

Ideal

+ 𝛼ir(𝜏, 𝛿)Rea𝑙

, 𝜏 =𝑇crit

𝑇, 𝛿 =

𝜌

𝜌crit

≡ Iterative calculation of thermodynamic states in two-phase region are very slowly

≡ Regression necessary

■ Refprop 9.1

≡ External access necessary but precisely

Refrigerant

AccuracySimulation Speed

Trade-off

17

Results of R410AAccuracy Refrigerant

Rela

tiver

Fehle

r in

%

0 10 20 30 40

Pressure in bar

50150

300

450

600

Sp

ecific

enth

alp

iein

kJkg−1

Phase change

Extended operation boundaries

Fixed operation boundaries

102

10−6

10−4

10−2

100

Result: Deviation of regression model < 1 %

18

Simulation speed results

Acceleration by a factor of ≈20 (Helmholtz) and ≈ 8 (External)

Negligible error in relevant range

Refrigerant

Model „FittedFormulas“

Helmholtz

ExternalStandardHorner

R410AR290R134a

Refrigerant

10

0

20

30

19

Implementation in ModelicaSystem modeling (BauSIM 18, MC19, GL2020) System

20

Transient simulation of a heat pump modelFirst results System modeling

Time in s

6000500040003000200010000

4000

3000

2000

1000

00

120

100

80

600050004000300020001000

Signal

Speed in s−1

Heating

load

in W

Heating loadSimulation result

21

Simultaneous consideration of design and operation

System structure and process design for heat pump

systems with refrigerant

Optimal process operation

minimizes costs

Optimal structure design

minimizes costs

Nonlinear interactions of both

Simultaneous method necessary Dimensioning = Design + Operation

22

System structure design optimization (GL2020/HPC21)

- 12% Costs

-16%

Em

issio

ns